1. Field of the Invention
The present invention relates to a driving system for a stepping motor, wherein the stepping motor is rotatingly driven by a predetermined steps when a driving trigger is inputted.
2. Related Background Art
Generally, in a facsimile and the like, a stepping motor is used as a driving source for feeding a recording paper or an original in an auxiliary direction perpendicular to a main scanning direction where the original is read and/or an image is recorded on the recording paper. As a method for driving the stepping motor, one-phase-on drive (1-phase energization drive), two-phase-on (2-phase energization drive or a half-step drive (1-2 phase energization drive) has been already known; however, because of ability of fine control and high maximum operating frequency, the 1-2 phase energization drive or half-step drive has been adopted to drive the stepping motor for feeding the paper in the facsimile system and the like.
During the transfer of the recording paper or the original in such facsimile system, since times required for reading the original in the main scanning direction and/or for recording the image on the recording paper differ from time to time due to image pattern of the original image, coding and/or decoding, the paper must be intermittently fed or transferred in the auxiliary direction, and the intervals between two successive transfers of the paper are not uniform or consistent.
In general, when the stepping motor is driven intermittently, for example in order to rotate the stepping motor at a speed of 800 pps, at the beginning of the operation of the stepping motor, the stepping motor has been controlled to be gradually accelerated by increasing the pulse rate, such as from 400 pps to 600 pps and then to 800 pps, or decelerated by decreasing the pulse rate. Such controlling technique is disclosed in the U.S. Pat. No. 4,340,848.
Such controlling technique is effective when the motor is rotated at a high speed for a relatively long time at a predetermined time interval as in the case where the recording paper is fed and/or a carriage is shifted in a normal printer; however, when the stepping motor is rotated intermittently with uneven intervals and the number of each driving pulses is very small such as 4 steps, 8 steps and the like as in the case where the paper is fed in the facsimile system, there arise problems that the stepping motor cannot be adequately accelerated by such controlling technique and the excessive time is required for the acceleration and deceleration of the stepping motor.